In recent years there has been a tremendous increase in the use of tissue cultures as a means of breeding plants. It is known that breeding by this method produces the best proliferation of the parent plant which was specifically chosen for its particular traits. Preparation of plants by this breeding method is carried out in the laboratory. The product available for purchase is in the form of boxes containing plantlets which were grown densely on a culture medium.
The farmer receives these boxes and must separate the plantlets from the culture medium and then plant each plantlet, one at a time, in the appropriate growing means, whether it be a growing tray, growing table or any other growing surface. The separation of the plantlets from one another and their replanting is hard and tedious work due to the fact that the plantlets are small and delicate and are densely packed together and entangled on the growing medium. For example, the height of the plantlets may be 5 to 10 millimeter while the width of the stems is less than one millimeter, and, in a box which is 11 cm by 11 cm, some 250 plantlets will be growing.
The results of this situation are three-fold. First, many plantlets are damaged during the transfer process. Second, many times the farmer is unable to separate the clumped plantlets into individual plantlets, so the planting is not uniform. Third, and most serious, is that due to the fact that the transfer process is so time consuming, there is often a significant time difference between the time the first plantlets are transferred to the new growing surface and the time the last plantlets are transferred when the farmer is planting a large growing area. This presents particular problems because plantlets at different stages of growth require different treatment and different environmental conditions. Thus, plantlets which are transferred over a relatively long period of time are often of different ages and in different growth stages by the time the transfer is complete, so the entire growing area cannot be treated at once and in the same manner. The great transfer time is also very costly. Finally, the produce of the farmer will not be ready for harvesting at one time, but over a range of dates corresponding to the transfer dates of the plantlets.
In order to fully understand the apparatus of the present invention, a brief description of the final stages of tissue culture in the laboratory is required. Plant material, which has undergone various processes during the growth process in the laboratory, emerges as plant precursors in the shape of objects similar to little balls or crumbs, which are called callus. These plant precursors are analogous to seeds.
The bodies of the callus are distributed on a nutrient base within boxes at a predetermined density. This density of distribution is required by the physiology of the plant growth. These boxes are closed and, by maintaining them in the proper environmental conditions in the laboratory, plantlets grow from the callus. Once the plantlets have grown in the desired size, the boxes, as stated above, are provided to the farmer who transfers the young plantlets to a different growing surface for continuation of their growth.